The present disclosure relates to an electrical power supply system, and more particularly to a Back UP Gate Drive Circuit to regulate a voltage in response to an over voltage fault condition.
Modules within an aircraft electrical system such as an aircraft Flight Control Computer (FCC) are often provided with redundant power supplies. In a typical rotary-wing aircraft, the FCC module utilizes a three phase PMA input source which is regulated to 34 VDC with a redundant 28V power supply sourced from a battery bus. A blocking diode in series with the 28V input connects these two inputs together at an “OR point” for redundant voltage input. If the PMA is connected and running, the shunt regulator's resulting 34 VDC output back biases the diode and allows operation off of the 34V input only. If the PMA is not connected, the remaining 28V input takes over operation such that one input is always connected. The “OR point” is the source voltage for the FCC module as well as for feed through power to other modules.
Although effective, an over voltage condition at the “OR point” source, which is normally regulated to between 33 and 35V, may damage the FCC module and those modules external to the FCC module.